Normally, articles such as bottles are loaded into cases by a case packer which utilizes a shift bar assembly which supports the charge of bottles from the bottom prior to dropping. While these shift bar assemblies work satisfactorily they restrict the speed of operation of the case packer in that all of the bottles forming part of the charge must drop completely through the shift bar assembly before a new charge of bottles can be loaded on top of the grid. In order to increase the production rate of the case packer, one particular case packer drives the conveyor feeding the bottles to the grid set at two separate speeds. Such a drive mechanism is complicated and must be synchronized with the drop mechanism.
In order to obtain high production in systems wherein a shift bar assembly is utilized, the infeed conveyor can be driven at a higher rate of speed to compensate for the lost time required for the bottles to drop through the drop bar assembly. One problem with driving the incoming conveyor at a higher than normal rate of speed is that the bottles are banged together as the charge of bottles are loaded into the case packer often breaking or damaging the bottles.
It is also important to utilize some sort of mechanism for holding back the flow of bottles onto the grid set while a charge of bottles is being loaded into the case. Normally, this is accomplished by overhead clamps that press down on top of the bottles.
One problem with utilizing clamps that press down on the top of the bottles when restricting the flow of the bottles to the grid set is that often creeping will take place since the conveyor on which the bottles are positioned normally continues to run.
Attempts have also been made to utilize stops that are raised vertically from the bottom into the path of the incoming articles. Examples of such a device are shown in U.S. Pat. Nos. 4,078,361, 3,325,967, 2,350,560 and 2,898,715. It is noted that in each of these devices, the stop is raised vertically into a gap provided between the bottles.
While some case packers in the past have utilized gripping arms for gripping a charge of bottles by their necks, it is applicant's understanding that only one arm of each pair of gripping arms was moved when dropping the bottle through the grid set into the case. As a result, the crown carried adjacent the top of the bottle would strike the fixed arm preventing a clean drop of the bottle into and through the grid set and also tends to loosen or remove the crown.